1. Field of the Disclosure
The present disclosure relates to a position information input system, and particularly, to a position information input system using ultrasonic signals.
2. Background of the Disclosure
Recently, various types of electronic devices including a mouse are being presented on the market as a position information input device. An example of the electronic devices is an information input device using ultrasonic waves. The position information input device using ultrasonic waves serves to input position information, by measuring a position of a pen-shaped signal generating device, based on distances between the signal generating device and ultrasonic signal receiving sensors, and a distance between the ultrasonic signal receiving sensors. In this case, the distances are obtained by using differences between a time when a reference signal (e.g., infrared ray, RF signal, etc.) has been received, and times when ultrasonic signals have been received by the ultrasonic signal receiving sensors spaced from each other by a predetermined distance, respectively. The ultrasonic signals which propagate at a speed of sound, and the reference signal which propagates at a speed of light are simultaneously generated by the signal generating device. An example of such position information input device has been disclosed in Korean Patent Publication No. 0418423.
In order to input position information using ultrasonic signals, required are a signal generating device, and a signal receiving device fixed to a position in a separated manner from the signal generating device.
FIG. 1 illustrates an example of a position information input device using ultrasonic signals in accordance with the conventional art, the device presented on the market. As shown in FIG. 1, the conventional position information input device using ultrasonic signals cause a user's inconvenience in portability and storage, because a pen-shaped signal generating device and a signal receiving device should be kept in an additional pouch or case.